The Oracle of Omaha is speaking volumes with his actions.

During the stock market meltdown in October 2008, The New York Times published an op-ed written by Warren Buffett titled "Buy American. I Am." Buffett noted in the article, "Fear is widespread, gripping even seasoned investors." But he remained optimistic.

Today, the picture looks much different. The S&P 500 ( ^GSPC 1.52% ) is near its all-time high. Investors don't appear to be afraid of what the future holds.

However, Buffett isn't writing an upbeat op-ed piece these days. Instead, he has quietly sent investors a $344 billion warning.

Buffett's $344 billion warning

If you really want to know what Buffett thinks about the shape of the stock market, look at Berkshire Hathaway 's ( BRK.A -0.13% ) ( BRK.B -0

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